I had mentioned the video fix for this board in Part 1, but I don’t believe I went over it beyond mentioning. So here it is, Ray Carlsen recommended resistor change for improved Video. These boards shipped with an incorrect resistor installed in the VIC II area, that reduces the level of the Composite Video output.
The resistor is R10 next to the VIC chip. His recommended fix is to add another resistor across the factory installed one. By doing this with the right value of resistor, you can get it set to the proper value. It is easier and safer to pull the resistor and replace it. Anytime you desolder a component you risk damage to the rather delicate circuit board traces. It can be done to look very neat as well.
You should be able to see the “stacked’ blue resistor overtop of the factory installed R10. This combination reduces the value to what it should have been. That did noticeably improve the video output. The factory resistor is 300 Ohms, the resistor that should be there is 120 Ohms. So obviously the signal is reduced. When putting a 220 Ohm resistor across the 300 that takes the value of the two resistors together to to give you around 127 Ohms, so that should be plenty close to the 120 that should be there.
So I managed to replace all of the electrolytic capacitors this C64. The Modulator was quite a pain this time around. Also due to that, I let my desoldering iron sit on idle hot for too long. The tip on it started to break down, so I will have to get a replacement. It worked well enough to finish the job though.
I know some people say replace the capacitors, some people say don’t mess with them if it is working correctly.
I say I hate desoldering the RF Modulator, but as far as something causing something I may see, if the modulator caps are going bad that will affect the video output. The RF Modulator is tied in and affects the Composite output as well, as it usually passes through the modulator. It turns out on this revision though the Composite does not go through the modulator, so it seems on this revision you can possibly just remove the modulator. I haven’t verified that though, and don’t intend to try it at this point.
Above I have prepped to work on the capacitors. They are there, as well as my iron and desoldering iron, and solder collection can that I expel the solder into from the desoldering iron.
As I said the modulator was a pain. They had not “turned” the ears on the modulator to hold it in, they had bent over the small pins. I had to work the modulator loose by getting what I could off and putting pressure on the tab I had loose and hold it down while it cooled, then work my way around. I also ended up pulling the 3 square pins up out through the modulator top. That was my best bet to not lift traces. By heating them with my soldering iron from the top side inside the modulator, until it could put pulled up with my pliers that I was holding the pin with. Once they were out of the way, it was one of those pieces they bent over that was stuck in the end making it so I could remove it. I did loose some of the bottom pads, or do a good bit of damage to them where they can is soldered in with the tabs. In the end it doesn’t look too bad, the one that fell off I put back in place and reapplied solder. The one square pin lost the narrow pad from the bottom, but not the through hole thankfully. It was the audio pin and that is why I decided to just heat and remove them pulling them up out. It was a good idea. They are a tight fit, so once I had them out, I ended up using a small file to file off the old solder so they would fit again. You don’t want them loose, because they are double soldered, you risk the solder loosing contact then.
After getting the modulator off, I replaced the capacitors in it, then went and replaced the remaining ones on the mainboard before reinstalling it.
I cleaned the tabs and such on the modulator body and the holes in the board to make sure it would fit back in easily. After that I reinstalled the cleaned up pins into the modulator. In the picture the center one had some solder on it again as I had started to reinstall it but pulled it back off.
I actually pulled it off, so I could check where the traces went under it, for those three pins. I wanted to be able to make sure they were making good contact before finalizing the work. So I reinstalled it, but I did not solder any of the tabs back tight before testing.
She still worked after the replacements. I haven’t tested the Keyboard or Sound though yet. Yes I was wearing an ESD Wrist Strap and working on my grounded ESD Mat.
After it tested good, I then twisted the tabs on the modulator and soldered all of that back on. I did a bit of cleanup of the flux and reinstalled it into the bottom case. Now I need to do that keyboard work so I can put this all back together and use it again.
The new tips came. I am going to be more careful about leaving it idle when it is not in use.
Here is my desoldering tip. I have seen this happen with Copper based tips, I guess this is Brass looking? If the hot solder is left on them it starts to dissolve the metal of the tip into the solder. It is replaceable, and I like the iron so ordered in a replacement for it. Once they start doing that they keep breaking down. Other types of tips will just burn the plating off and then will quit accepting solder and not transfer the heat properly. I will not leave it idle like that while it is on again. It was while I was working with the modulator, which may have taken a hour. I was taking care to not wreck it, so it took awhile.
Beyond the modulator it was an easy recap. Most of the capacitors I pulled tested pretty reasonable but not all.
Three of the 10uF capacitors tested with almost no capacitance. Otherwise they were a little inconsistent and all of them measured above their stated values. The new ones are closer to their rated values. With those three odd ones, I feel it was worth it.
Well on to revisit the keyboard. I really don’t want to take it apart again, but the * key is kind of important. So I will get that in the next and likely last post on this refurbishment.
I didn’t think I could do much with the tab, and with the two cracked screw standoffs, I figured it was worth while to get it. I will have to say I am very happy with the fit and quality of the parts. I attached them with some JB Well 4400psi Epoxy.
I am doing another coat of paint on the lower portion of the case, partly in hopes of a sturdier finish, but also due to that crack that showed at one of the Din ports in the back. I had glued it, then I used some Epoxy on the inside to help it as well. I then used the White Putty in the crack to help blend it out.
With the top I cut the broken portion of the case tab off. It was the narrow one. I then installed Birt’s replacement tab. It was a perfect fit. Per his recommendation I did slightly round its edges and the two remaining tabs. I also put his parts on to reinforce the cracked screw standoffs in the top. I again used the White Putty on the outside of the crack in the right front corner of the case to help blend it out for the paint. While I had the epoxy, I decided to reinforce the inside of that crack with it as well.
The paint turned out really well. I put on about 3 coats on it. Krylon Fusion All in One Matte River Rock.
I ordered in some reproduction badges for the top of the case. Well I went with the “gold” model type labels. This thing is an odd machine, and the reproduction badges are great, but the way they are made is a bit different so it was not going to look exactly original from close up. So I am happy to make this rather neglected, and somewhat unique 64 look a bit more unique.
I have just finished replacing the electrolytic capacitors on the board. That will be posted in Part 3. The modulator was quite a pain this time around.
I still need to look at the * key and see if I can get it to be more responsive. The two “repaired” plungers are a bit off, the height is just a little wrong. I am going swap them out and keeping them as future spares. I need to open the keyboard to check out the * key anyways, I might as well switch them. I may redo them with epoxy sometime and try to adjust the height a bit more. I don’t know if that will be Part 4 and hopefully end up with it finished up.
I picked up another Commodore 64 breadbin model. It had a rough time in storage from the looks of it. The system has been in a damp dirty storage area, there were several of them being sold by the same person, in similar conditions along with some other old 80s era computers like Apple ii systems. I guess they were stored in a basement somewhere that had some real water/moisture problems.
As you can see from the outside it is a bit dirty, and some keys were missing. This was I think the second best looking of the batch. Below you can see the inside, the paper shield was a mess, black mildew along the bottom. A good bit of dirt inside. After seeing it in the bag, I decided I wasn’t even opening it inside. So I took it out back and opened it there. I removed the cardboard shield and it went strait to the trash can. The case was then hosed down to get the worst of the dirt off. I wiped the keyboard down a bit and the board before taking them in. The case parts went it the tub and got a really good scrubbing.
I removed the RF Shield and cleaned the board with some 91% IPA. It turns out to be a bit of an interesting board. Yes the screws are mostly rusty, the RF Shield and Cartridge port plate tells a tale of too much water too. On close inspection the board looks ok for the most part, the legs of some of the components are rusted, I clipped a them and the tips just fell off. This board has obviously been worked on in the past. The inner cardboard sheet that was above the bottom RF Shield went strait to the trash, it was about as awful as the upper cardboard shield.. I kind of like this brass looking shield, but without the cardboard to go with it, I won’t be reinstalling it. I don’t care enough to make a new cardboard piece.
You may notice the wires in the above picture. This is a 326298 Rev A board. An early board that only has the 5 Pin Video port. This board was built in 82 based on the unsocketed chips. The board had extensive work done to it. All of the main chips are socketed. They are all dated second half of 84. The 5 Pin Video port was replaced with the later 8 Pin Video port. There are two wires running off from that port, and various cut traces on the top and bottom to separate out the additional pins. I think in the VIC II area there were possibly some other changes. The VIC II area cage was (and still is) rather rusted as well as the RF modulator top plate, and the RF RCA Port was all rusted.
So after the ipa bath I hooked up the board.
It worked, no issues. Next I tested the keyboard, it worked, minus the two broken keys. Some keys were not very responsive though. I did a full teardown of the keyboard to clean it properly.
I first removed all of the keycaps with my keycap puller. I recommend one, they are rather cheap and good insurance to prevent breaking the old plastic. I next desoldered the wires on the ShiftLock key. I had removed the tape from around the keyboard, as you can see, to get to the screws under it. After removing the screws the board lifts off, and you can see the plungers then.
I took out the plungers and put them to the side, then took the keyboard frame and sent it to the tub and some warm very soapy water. I also soaked the keys in the soapy water. Then scrubbed the keyboard and keycaps with a toothbrush and rinsed them well and dried them. I also took the springs which were dirty and some were rather rusty. I put the springs into some White Vinegar. The Vinegar removes the rust, it does make the metal a bit dull looking. I expect if you leave them in too long you may break down the metal too, so I kept checking on them. They cleaned up well, the worst of them you could tell were actually pitted but were still in working order. I then washed the vinegar off with some water and dried the spring as best I could. I placed all of that on a towel to dry properly.
While that was drying, I took some IPA on a qtip and lightly wiped the contacts on the circut board. We don’t want to remove the conductive coating. If you clean too much of it off they keys won’t work. Next I took the plungers, and wiped the shaft part with a damp cloth to get any dirt off, I didn’t wipe the contacts on the plungers, they looked pretty good. They were mostly clean overall due to being covered by the keycaps and in the keyboard frame holes.
All of the good plungers and two broken ones.
Well, I had watched Perifractic’s Lego 64 videos, and I got an idea to try on the broken plungers. They did still work, as I had tested the keyboard with them, they just won’t hold a key now.
So I found a Lego laying around. You see the full piece I started with there in the lower left. I cut it in half, cleaned the plunger up and fited it to it. I shaved it down to go into the plunger shaft a little for more surface area and strength. Then I glued it in with a combination of Bondic and Super Glue gel. I did have to file down the Lego piece, it was too large and the Commodore Key cap wouldn’t go on it. I used my small Diamond Grit Needle Files from Harbor Freight (they are just small files, I got the Diamond Grit ones, they seemed to work well for me on plastics). I will say that the glue doesn’t hold well, these tops will come off. So it isn’t a great fix, but I think it will work. I am still waiting on replacement Plungers and springs for the keyboard. I put the one plunger back at the British Pound symbol location, but I put the other at another key that is less likely to see much use. The 8 key gets a lot of use.
Here is the keyboard frame after reassembly.
Here is the keyboard back together back in the cleaned upper case. I tested it and it all works. The * key doesn’t work very well though.. When I get the new plungers in, I will probably remove the circuit board again and check that key. I don’t know if it it is the plunger, or dirt, or the contacts on the circuit board. Other than that and the missing caps, the keyboard was quite responsive, better than my other C64. That one I did not remove the board to clean the contacts. Removing to swap the plunger and check that key isn’t too bad. I will only have to desolder the ShiftLock key and remove the screws. The plungers that I am not working with will all stay as long as the keycaps are still on the keys can’t come out.
I does look much better than it did, but it is very streaked. The Power LED plate was actually corroded to the point much of the paint was lifted and flaking off. Corroded Aluminium.. Ya, I guess a good bit of moisture for a long period of time. I plan to get a replacement Badge and maybe a matching Power LED plate, I just don’t know what I want to go with.
Next I started on some preventative maintenance as well as rust removal. I had already removed the rusty tops of the VIC II area and the Modulator top cover. I then desoldered the Cartridge Plate and the VIC II cage which is rather rusty. I did alot of cleanup on the RF Modulator cover and Cartridge plate. A combination of wire brushes, sanding, and polishing with the Dremel etc. To remove the stickers easily, I put a little WD40 on them and let it sit. When I was done they were pretty decent. I tried some Vinegar on the RF Modulator cover, but that removes the protective coating that was still on some areas of it, so I stopped that. I did soak all of the rusty screws (basically every screw in this thing) in the Vinegar to get the rust off. I also removed the Fuse holder pieces, and fuse, they were quite corroded. I placed them into the Vinegar as well (well not the fuse). The Vinegar did clean the corrosion pretty well off the Fuse holder, but it left those areas black, I then polished them back to a shiny surface before reinstalling them. When all the rust was off of the screws and Cartridge plate and RF Modulator cover, I put some “Teflon Non-Stick Dry-Film Lubricant” on them. Not to Lubricate them so much, but to put a protective film on them to help prevent them rusting again. I did the same with the keyboard springs after they were dry. I don’t use the stuff on plastics though it puts a white film on that is hard to remove. So I put it on before putting them in place.
I resoldered the Cartridge Plate back to the board. I also touched up some solder points on the board. The VIC II cage will not be going back in. I think the VIC will stay cooler without it, and with a proper heatsink installed.
Here is the board reinstalled after cleaning up the rusty bits.
The board was tested again and still worked. So next I installed a few heatsinks.
The 5 Volt Regulator doesn’t have much of a heatsink on it. The Rivet is loose and the heatsink is spinning around. So I decided to remove it and fix that as best I could. I took the heatsink off of it. I placed it on a new 2 Amp capable 5 Volt Regulator, it wasn’t needed, but that is what I keep around. I was a concerned that with the age and heat that Regulator dealt with over the years plus that loose tiny heatsink that it really should be replaced before it fails. When these regulators fail they most often fail open, meaning they will push the full voltage through them instead of dropping it or cutting off the voltage completely.. That fries the ics in the board. I have not heard of them failing inside the C64, while they are the big issue inside the C64 power supplies. With that very tiny heatsink, which was also not making good thermal connection to the regulator I didn’t want to take a chance on it. This time I put a second folded back heatsink behind it with thermal compound between the heatsinks as well as on the back of the regulator and bolted it all together.
This change to the Heatsink is an improvement, I guess. Still it seems very inadequate and gets very very hot.
As far as the case repairs go, I guess I didn’t take any pictures to show that specifically. The top of the case is cracked in the front right corner, it appeared to have taken a hit to that corner. It also has 2 cracks in some of the screw supports. I used my solder iron on a lower temp to melt the inside of the crack in the corner of the case together again. Then I put some liquid Testors Model glue in from the back to smooth it out. That did start to melt the plastic, I removed the excess glue. I have found that if you use that stuff and it melts the plastic and there is too much excess glue the plastic won’t harden again. The one standoff in the top of the care there is cracked as well, I haven’t fixed that yet, I think maybe from the same trauma that cracked the top. Three of the standoffs that hold the keyboard in place were sheared off as well. Those I glue back on with superglue gel. I then clamped them for a day and left it sit. That will give me the best strength, they shouldn’t be stressed while it is curing, which is 24 hours to get to full strength per the manufactures directions that is. The clamping ensures they are down properly and the joint is thin and tight too. After that I put some Bondic glue around them, the Bondic won’t cure in the crack because it needs UV Light to cure. I have also found it doesn’t bond very well compared to Super Glue. It does retain some flexibility and have some hold, I find that can assist Super Glue because it holds so tight, but doesn’t flex and fractures.
This case is badly discolored and I don’t want to try to retrobright it. I picked up some Krylon Fusion All-In-One Paint+Primer “Matte River Rock” paint awhile back to potentially paint a 1541 case. The case had some small chips out of the bottom. I took some Tamiya Putty “white” and filled in and built up the missing areas. It is a potent thin putty that dries quickly, and sands well for me. I it seems to bond to the case plastic well (As the model glue fuses the plastic, so I would expect the model putty to grip it well too). When I was done with the physical repairs to the bottom portion of the case, I put a even coat of the Matte River Rock paint on it. It turned out well. After the paint dried I found a crack show in the center of the half circle of the video port in the middle of the case. I glued that with the Testors Liquid model glue, I hope it holds well. Later I will put on some epoxy to help give that crack a little more support (I should have used Epoxy on the keyboard plungers instead) . I think once the board is reinstalled it will have more support where that crack is as well.
I haven’t done anything to the top of the case so far except weld and glue the one crack. The one case clip on it is broken off and lost. There are also 2 screws posts in the top that are cracked. I have thought about getting one of Birt’s “Hey Birt!” case saver kits to get a new case clip, I could use one of the reinforcement pieces on the cracked stand off, and have spares for the future. As I have to fix that case clip, I don’t want to paint the case yet, I will likely scratch up the paint having it upside down for those repairs. I will put several coats on the case. I want to test the paint on something with a Matt Finish clear over it. Some paints don’t mix well, and can cause the lower paint to lift or got to a crackle like finish. I have found that even with paints from the same company.. So I will test the Krylon Matt Finish first on a scrap of similar plastic (probably a modern computer case bezel). I want to put the clear over it, even though I like the existing Matt Finish of the paint as it should help protect it better.
So for now that is about it for this C64. In the future I will be doing more to it. The remaining repairs to the case. That include the Clip and post repair as well as painting and installing a new Badge plate. Checking out the * key, as well as installing the replacement keys and springs. I also have a capacitor replacement kit for it. With the 84 Breadbin I already worked on, I had found some capacitors that showed evidence of failing, so I figure this one is going to be served well by replacing them. I do wonder if that, especially the ones in the RF Modulator, may make a difference in the video output. I may or may not install some additional heatsinks. The computer is working fine, but it does have bad jailbars, so I may do something with that too at some point. I don’t know of removing the modulator and building up a replacement would help that or not.
I would love to know where the other Breadbins that were sold with this ended up and see that they were properly cared for. There was a very interesting VIC that I would have loved to see, but I wasn’t paying that kind of cash for a VIC let alone one that looked like it spent a few years sitting in water.
Lets see what was left after the last post. There were quite a few changes to the board layout. I found several defects in the circuit diagram I had made.
There were corrections for the Pi1541 section, in that I had connected up one of the signals that I shouldn’t have. The removal of that bit made the design a bit simpler actually.
For the Tapuino side I had several missing connections. So the layout below is not the exact same layout seen below here. This one below is the corrected revision with a few additions as well.
Gerber Files for the board can be downloaded from here:
I built the Pi1541 section based on the Option B design, but with the additional signals wired in that were listed but not wired. That is why I have the second level shifter on the board. I sort of think of it as an Option B+ design, there are some others out there, but most are just plain Option B. It didn’t matter originally, but for some of the new features he has been working on, the additional signals are needed. The problem though was that the oAtn or OUT_ATN should not be wired up as it will never be used, so I had to remove that and I had to do some modifications to my prototype board below. I also added the Buzzer for the Pi1541 to the board design. The next changes were the missing connections to the 4052N on the Tapuino section. I was missing 4 lines going to the IC, two being ground and two to the ATMEGA pins. Some other additions are Read and Write LED Indicators to the Tapuino.
The board I etched was no the above design, to correct my prototype board, I had to cut the lines to the oAtn, removed the wire from the pin on the Pi for as well. I have added wires for the missing traces to the ATMEGA from the 4052 and grounded the other two pins. My buzzer is on the Pi header not the board, and I don’t have the additional Tapuino LEDs.
The images of the board below are the board made with the previous design. That is why it won’t look exactly the same. Some pictures show the corrections and some show how it was originally assembled.
First let us start of with the Toner Transfer process. To do a toner Transfer you need a piece of glossy paper. I initially purchased some Toner Transfer Paper, it was rather pricey for all the more use I get out of it. With Eagle I can not find how to “tile” my printout, so I am using a full sheet for any tiny board.. I found you can use magazine pages, so I tried that. It has worked out pretty well actually, although The first run didn’t. This is a more complex board, it is double sided, and it really is not easy to line it up properly. To do so, I printed out both sides. The top mirrored and the bottom not mirrored (as the bottom is printed mirrored already). I then lay them on top of one another and with light behind them I get them aligned. I then cut the sheets down. This gives me some registration of the alignment. I double and triple check alignment. I tape the two sheets together on two opposite edges with clear tape. I do not want the tape to overlap onto the circuit board material, so I had around a inch boarder around the board printout. If the tape overlaps the design it can make it not transfer properly. We need no assistance in having a failed transfer, that is easy enough to get without additional help.
That being said here is how my first try went.
My next attempt went much better.
With that transfer I just had to touch up some places with a sharpie in the ground plane areas. It was not easy to etch though. It took quite a few passes and pulling the board out as the toner ended up starting to lift in a number of areas. I don’t know if it was my toner (I think it is at least partly the aftermarket cheap toner), or the extended time it was taking in the etching solution for me. I was just using peroxide, vinegar and salt. It was taking a long time. I don’t have anything stronger here, but due to the time it took, I may try to pickup something else in the future.
Below is the completed board after etching compared to my printout samples. There is one bad short, I don’t know why it did that there. There are some areas that were a bit close. The transfer process is to put the board between the printouts, and use heat and pressure to transfer the toner from the magazine paper to the copper. The copper must be very clean and not tarnished. I sanded it with fine sandpaper, then cleaned it with some rubbing alcohol. You want “enough” heat but not too much, too much and the toner melts and deforms, to little and it doesn’t transfer. Too little pressure and it won’t transfer, it seems the more pressure the better. I use a small iron that I can put a lot of pressure on, but I don’t find it easy to do. Once the transfer is done (or you think it is), then put the board into some water. The magazine paper will break down and come off leaving the toner on the board (if it worked). Carefully wipe it off to get that white paper haze off of the surface. Then put the board into the etching solution. (I have some examples and details of the process on my Commodore Computer Saver post, which is a more recent post here.)
I was extremely happy to find out my alignment was nearly perfect. It etched well, although it took forever. This is the second board design I have etched, and only the third board. The first being an adapter board that was extremely simple. The other design I did, I had the traces closer together with less empty gap. The wider gap I had here between traces made it much easier to solder up as there is no solder mask present.
The next step was to drill all of the holes. That took awhile. It required some very small drill bits. I had picked up a set of very small bits from Harbor Freight last year for very little cost. They turned out to be perfect for the job. The only problem is it would have been forever with my pin vise drill. I went to the drill press (from Harbor Freight as well), and well it couldn’t hold bits this small. Well my pin vise drill is metal, and round if I take the bottom piece off. I carefully installed it into the drill press chuck. I tightened it just enough to hold it and left the other bit holding part inside the shaft of the pin vise to make it stronger.
I then went ahead and drilled out all of the holes. The smallest being the holes for the resistors and capacitors. The last board I did, I drilled some of the holes a bit large, that made it hard to get the leads to solder in with too much gap around them. This time I went with the closest size bit I could. That ended up being about 3 primary sizes, the smallest for the resistors and capacitors, then one for the Dip sockets and finally the pin header and other connectors. With a few larger ones for the mounting points on the PS/2 style socket and board mounting holes.
With this being a double sided board, and no plated through holes I had to pay special attention to assembly. I used Machined DIP Sockets for the ICs, as the top side of the pins can be accessed with them tight to the board, and some of the connections are only on the top of the board. I didn’t have a Machined socket for the ATMEGA, so I used machined strip headers for it taking care to make sure they were standing up strait. I did not assemble this board in the order I would if it had been a manufactured board with proper through holes. Normally I would put in the short stuff first, then the taller stuff later and the tall connectors last. I couldn’t do that, and get to the areas I needed to on the top side.
Dry fit on the left, soldered on the right. Because of the non plated through holes, you see a bit of solder on the top side where I had to solder to the top side. The Pins for the Level Shifters (and the other header pins) were soldered by sliding up the plastic bits to get to where I needed top side soldering. I then slid the plastic back down the pins. The Level Shifters were then soldered on from above.
As I mentioned above there were some changes to the board after I etched it. The above image shows it as it was made initially. Below here is the revised board with the corrections. The removal of one resistor in the Pi1541 area, I also removed the one header by the Serial port due to there having been a short under it I had to remove. I didn’t need that header in there for my exact use. That header would be used if you wanted to put in a Second Serial port like the real 1541 has instead of the PS/2 type port I am using for my 7″ LCD interface. The same header coming off the PS/2 port wires to the removed header above the Serial port to enable it in that case. The cutting of one trace in the Pi1541 area by that resistor on the bottom side of the board. The additional two wires for the Tapuino between the ATMEGA and the 4052, as well as the added. Ground pins connected up to it. Again the below changes don’t need made to the “newest” design. These modifications are due to the earlier defective design I etched this prototype from. If you compare them there are quite a few changes between it and the revised design at the top of this post. This is how the board is in my drive now though. I have the Pi Buzzer for the Pi1541 directly on the GPIO of the Pi. I don’t have the Read and Write Status LEDs for the Tapuino, although I am thinking of adding them. It is worth noting that the pinout for the header that is going over to the Pi’s GPIO is different on this earlier board than the revised board. The changes were to move the Buzzer to the board, but also I swapped the positions of two of the signals to simplify the traces going to the Serial port.
The Silver “Stripe” marks on the top of the board are marks for Pin 1 of the various Headers.
Here I have the board installed into the chassis.
You may wonder about the Black Oval thing in the middle on the right, that is a Ground Loop noise isolator. It is between the Pi’s Audio Jack and the Audio Jack of the Little audio amp at the bottom of the case there. Without it, there is a buzz. I have used a couple of these things now for that kind of isolation. I believe they are essentially a transformer inside, so there is no direct electrical connection between the grounds.
I had mentioned in the last post that there was an issue with the Meanwell power supply needing a 200mA minimum load on the 12Volt rail. My solution to that problem was to install two 100mA rated fans. The one I put on by the little audio amp. The ic on it gets warm at higher volume levels, so I figured it was a good idea. The other fan I put on the top of the case by the Pi to cool it. The fans make very little noise and provide enough load to the power supply to be happy even with the Audio Amp off, which also runs on 12Volts. I don’t believe the fans are are really pulling 100mA, but they are close enough that everything is working well.
Yes the Pi1541 is working.
Here are some shots of the exterior of the Pi1541/Tapuino unit.
The Tapuino section is also working as well. Originally though, I couldn’t get the Tapuino to work with the 4052 installed. So I bypassed the 4052 with some jumpers into the IC socket and I was using it that way for awhile. The 4052 is not needed unless you want to be able to duplicate from another device into it. I put it in the design to have it “complete”. It lets you connect up either a physical Cassette and dub off of it, or another Tapuino (why?). To use it, there is the unused red header there in the Tapuino section that would go to the other device. I eventually came to the conclusion that the likely fault was the specific 4052 IC I was using. I was trying to use some 74HTC4052N ics, and they just wouldn’t work. I ended up ordering some 74HC4052N ics, and those worked perfectly. I try to be careful when ordering in ics, and the fact there are so many similar models it just doesn’t always work out. I don’t know what the difference is in the HTC that it won’t work in the place of the HC chips for this use. For the old 8bit stuff usually you use LS stuff, but these don’t come in LS. If you don’t want to duplicate tapes to the Tapuino, then you really only need to bypass the 4052 with two jumpers, you could even leave out the IC socket and jumper on the board.
I would like to post the board design in some way that it can be downloaded by others that may want to try to use it. I don’t know about making Gerber files though, I could post the Eagle files somewhere and then someone could do Gerber files themselves. Eagle is free for these small designs.
I picked up another Commodore 64 quite cheaply. This poor system had been stored in some bad conditions. I am not sure the conditions, but it had been wet at one point at least and damp quite a lot. When it was put there, it was probably pretty rough looking as far a browning of the plastic. This was an early Commodore 64 from 82 originally. Oddly the serial number label had no serial number printed on it. I have seen some labels that ink can be removed from by some cleaners, so I don’t know if it had been wiped off or never had a number.
Internally it as all there. The old paper foil shield was dirty and had mold on it. There was dirt and dead bugs all inside it. The first thing I did was pull the paper shield and toss it out, I then pulled the keyboard and mainboard out. Next I hosed the worst of the dirt and bugs out of the case with a hose.
Next I removed the bottom shield from the mainboard. It showed quite a bit of corrosion on it.
Before I tried to fire the board up, I did a bit of cleanup on the board itself. Then I looked it over to see if anything needed addressed before trying to power it on. I first checked that the power switch was making good contact. I then checked the Fuse was good. I also pushed all of the socketed chips in to make sure they were tight.
Looking over the board it was dated as 1982. There are some odd things about this board, it has had all the main chips socketed (all “wide” chips). The main chips are also all dated 1984. Three of the ram chips have been replaced and are also dated 1984. The remaining chips are all from 1982.
Here you see all t he main socketed chips. CIAs, the 3 Roms, the CPU, SID, PLA and VIC II from 1984
The next odd thing about this board is that it has a 8 Pin Video Socket instead of the 5 Pin Video Socket that was originally on it. julrod over at Lemon 64 said he had heard that Commodore service centers had upgraded the 326298 boards with 8 Pin Video Sockets. I have yet to test if the 8 Pin socket includes the added Chroma signal for S Video like video output (It does work and it works very well). Looking around the 8 Pin Video socket I saw 4 cut traces (some on the bottom some on the top) around it and there are two wires on the bottom side leading off to points on the board.
Here are the two wires off of the Video Socket, you can see some of the cut traces too.
I connected the cleaned up board to a display and my power supply. It actually came up to the normal startup screen showing all of the memory. The video was noticeably poor compared to my other later Commodore (a 1984 model). It has bad Jail Bars on the screen for one. I then connected up my full test harness an test cartridge. The board passed all of the tests. I fired it up with my Pi1541 and started up a game.
The next day I spent doing a lot more cleaning of the computer. The case was cleaned with some CLR Mold and Mildew cleaner, a brush and a toothbrush. It still looks bad due to the lack of the badge, the bad browning of the plastic. The plastic is streaked oddly in the browning as it isn’t very uniform. The top has a crack on the right front corner. Three of the mainboard mounts are sheared off. The narrow right tab is missing that holds the back on. Two keys are missing and the posts are broken on the keyboard. The keyboard worked, but it wasn’t very responsive. It is quite dirty as well of course.
Most of the screws are rusty. Some of them are very badly rusted, anything in the “front edge, including the case screws. I put them into some vinegar. After soaking in it for awhile, the rust was removed from them. It left them looking a bit different, but they were in much better shape. I also did the same with the keyboard springs.
I removed the cage around the VIC II area. It was quite rusted, and I don’t like them anyways, as it makes it hard to get to the parts inside. It may be a decent heatsink for the VIC II though, I replaced it with a real heatsink though. The computer has a factory mistake where R10 by the VIC is 300 Ohms where it should be 120 Ohms. Ray Carlsen recommended putting in a 220 Ohm resistor in parallel across the existing R10 to bring the resistance to what it was supposed to be. This corrects the resistor in at R10 brings the strength of the Composite Video output to what it should be.
Here you can see the new Blue 220 Ohm resistor stacked on the original R10 just to the right of the VIC II
Here is the keyboard disassembly.
I lightly cleaned the keyboard pcb with some IPA. Once it was put together again, it did seem like it was more responsive. I haven’t tested it fully though. Keep in mind that too much cleaning of the contacts will rub the carbon off and they won’t work properly.
For the keyboard I turned to a little inspiration from Perifractic at Youtube. I had to tear down the whole keyboard to clean it properly. It also wasn’t making good contact on some keys, so I decided I would clean the pcb on it. I don’t have spare keys, or posts. I decided I would try repairing the broken keyboard posts with some pieces of Lego Cross posts. It does look like it may work, I don’t know for how long though. The one key the “pound” key is one that I doubt I will end up using, so having a repaired post there shouldn’t be a big deal. The other key was the 8 key so I decided to move that post to another position where it will get less use. To do this was a combination of a drill bit, using a Dremmel, and Xacto knife. While the Lego Cross axel looks like the key post top, the problem here though is that it is just a bit too large. A Lego piece that accepts the Cross Axle will go on a Commodore Post, but a Commodore Key won’t got on the Lego Axle. I don’t know if some of the Lego Axles are a little different or what though the ones I had wouldn’t work with the keys properly. I ended up using a small file to file them down to a more fitting size. I found that superglue won’t get a great bond on Legos, Bondic doesn’t either. I did try some model glue, which was said to be able to fuse Lego pieces. I don’t know how well it is holding. I may eventually replace the damaged posts, but for now they are hopefully ok. I still need to get 2 springs and two keys.
I reassembled the keyboard with the repaired posts.
I also took the top off of the Modulator and cleaned and polished it up. The plate on the Cartridge Port had some bad rust on it as well. I desoldered it from the board so that i could get it properly cleaned up. They both turned out to be a good improvement. I was going to paint these pieces but decided not to. Instead I put some teflon liquid to try to protect them from rusting quickly. I also used it on the screws. It puts a bit of a coating on stuff and is used to protect tools from rusting as well. The other part/parts I pulled to clean up were the two parts of the Fuse Holder. They were badly corroded. I desoldered them and polished them.
The board now looks quite a bit better. I also installed heatsinks on the VIC II, SID, PLA, and CPU.
The conditions left the metal plate around the power LED corroding and the paint lifting off. I ended up cleaning it as best I could. I have to figure out what to do with it for painting etc. The main case badge was missing, and from the condition of the browning of the plastic , it must have been missing for a good while.
In an effort to get the old case looking a little better, I scrubbed the case with a paste of Baking Soda to get some of the marks off of the plastic. It did get rid of some of them. The plastic is still streaked brown.
For the crack in the right front corner on the top, I melted the plastic from the inside with my solder iron set to a lower temperature. This held the part in place, but for the crack on the outside, I used some model glue, that seems to have fused the plastic there pretty well. I also put a little on the inside to even out the melted plastic. Be careful about getting too much of that stuff on the plastic, it will dissolve it making it soft. It may not harden properly again if that happens.
Some of the pins in the components were rusted, and rusted badly on the bottom side. So I thought I would just clip them closer to the board. When I clipped at least two of these they just came right off. They were rust clear to the solder. I don’t think they were rusted below the solder. I tried to remove as much rust as I could. The presence of rust encourages the formation of more rust unless I am mistaken in what I have heard.
So far restoring this old beat up 64 has mostly been a lot of cleaning and some physical repairs. I did do the R10 fix. I still have more to do with it, and I am not sure when I will find the proper replacement keys. I was thinking of just ordering any key to put on the keyboard so I have a full keyboard, but I am not sure yet. I will probably recap the board. I have to fix those 3 board mounting standoffs that are broken off. I may fix the broken case tab on the right as well. The heatsink on the 5 Volt regulator is a bit loose, so it won’t be making the greatest thermal transfer to it. I will see about fixing that up before using the computer too much as well.
I am looking at the options for replacing the case badge. I also plan to paint this case and not to try and retrobright it or anything like that. The letters on the keyboard keys are also yellowed. On the left side it isn’t too bad, but as you go across the keyboard it gets quite bad. This computer will never be the best show piece. I think I like it though for the 8 Pin Video on the early board, and the main chips being socketed. I could easily use this board to test most of the typical breadbin primary chips. Being is such poor physical shape gives me a bit of freedom as this case will never be “like new” again, I can do what I want and not have to feel like I am harming it. It is a bit unique and it will remain so. I didn’t check the Chroma output on that 8 Pin video port yet, but I will get around to that probably later this week.
Once I was done cleaning it up, and I finally put the keyboard back together I fired it up again to try out a game again. I “think” it looks a little better onscreen. It still has noticeably worse jail bars than my other Commodore 64. I am only using it on my little 7″ composite display so I don’t know how bad for sure until I put it on a bigger display.
As I make progress on the restoration of this Commodore 64 I will probably do a followup post on it.
My 1541ii didn’t come with a power supply. I initially tested the drive with some pins on power leads from my variable power supplies. That worked to test that it was functioning. It certainly wasn’t the best way to use the drive long term. I had a MeanWell dual output 5Volt and 12Volt supply I picked up for another project and had ordered in a 4pin Din connector. The next time I used the 1541ii drive, I had wired it up with that drive. Well right as I started using it the drive failed on me (see prior post). It turned out the SRAM failed for some reason. I don’t know if it had anything to do with the MeanWell supply or not. That supply requires a minimum load on both outputs for it to work properly. I don’t know if it wasn’t getting that load and was sending the wrong voltages to the unit.
After that I went back to using my regulated variable supply for the 12Volts and a 5Volt fixed bench supply I have to test the drive from there on. The MeanWell is intended for another project, but it my not be used for that project either as I don’t think I will be providing the “minimum load” on it.
I decided to order in a used dual voltage power adapter from Ebay to become the new supply for this drive. The one I picked up is 5Volt 1.5Amp and 12Volt 1.5Amp. So it is more than sufficient for the job, provided the quality and condition of the unit is good.
The supply I picked up to convert for the 1541ii
All I really needed to do was cut off the existing 4Pin Mini Din connector and replace it with a properly wired 4Pin Din connector. While I could have purchased a cheap new supply and done the same thing with it, I felt this “old” supply was probably going to be better quality than the cheap replacements. It did come in looking a bit dirty like the picture above, but it cleaned up well and tested fine.
Here is an image of an original supply. Notice the Pinout there. Only 3 of the pins are used on the 1541ii Supply. It is said that the ratings on these original supplies were rather low, potentially causing them to overheat and be unreliable. That sounds a bit like the original Commodore 64 supplies now that I think of it..
Image of an original supply.
Here is the supply with the connector changed out.
While I don’t normally wire the “ring” of the Din Connector up to anything, I did wire the second ground to it as it was a convenient way to keep it out of the way, and I don’t know if that 4th pin goes to anything inside the 1541ii. I probably should have taken pictures of the connector before closing it up.
After soldering on the wires to the pins in the Din connector I insulated all the pins and wires with Liquid Electrical tape. It has a bit of hold to the wires, but mostly is to help prevent shorting in the connector in case a wire pulls loose. There isn’t much room in there to get normal heat shrink on the pins, as it is best to keep the casing to wrap the clamp part of the connector to. I did the same thing with the Commodore 64 power connector, and my new video/monitor cable.
I did put a piece of heat shrink on the cable under the strain relief cover of the Din plug. That piece of heat shrink builds up the end of the cable just a little and makes the strain relief bit grip well. Without it, that relief tends to pull back easily and will likely tear prematurely. I have done the same thing on my Commodore 64 Power Supply’s Din plug. I wish I had done it with my new video cable I made. My old original video cable could have really used it as well, but I don’t want to take apart the connectors and redo all of the soldering on them. There is a bit of risk in damaging the Din plugs as they melt easily when the heat is applied to solder and desolder the wires.
The supply seems to work fine with my 1541ii. The Din Plug quality is rather lacking though, I think it will hold up ok, but the fit isn’t the nicest.
Watching some videos, I noticed the 1541II had a grounding wire going from the one screw on the mainboard up to the right side of the drive assembly. I happened the have a braided ground cable of approximately the proper length that I salvaged recently and was on the bench still. I cut it down a bit and soldered a second lug to it and put some heat shrink on that end. The original one that I saw was not insulated, but as this one was already covered in heat shrink I figured I would leave that. I also picked up some new 10uF 25Volt Panasonic Electrolytic caps with my last order from Console5.com. I figured I would swap out the 3 original capacitors on the board. I went ahead and replaced the capacitors and reassembled the drive with the additional of the grounding strap. I had rigged a Meanwell dual voltage power supply with a power cable for the drive and figured I would test it out. I fired up the Final Cartridge III+ and brought up the Disk utility and checked the status of the drive, it came up normally. I attempted to read the disk and it failed then it started blinking an error. I turned it off and reset it and then it only blinked the light with a somewhat slow blink and kept turning the drive.
I rechecked everything, made sure again the capacitors were installed correctly, that nothing had shorted. That the power supply was supplying the proper voltages. I swapped the VIA chips. The board is fully socketed, so I removed and reinstalled all of the chips. I used my IC identifier on all of the 74 logic chips and they all read fine. I don’t know if that IC checker is just an identifier, or if it really checks for proper operation. I also tried both in normal mode and in JiffyDOS mode.
After all of that I also tried powering the drive with my fixed 5 Volt linear power supply and my variable regulated supply set to 12 Volts. The same results pretty much every time. I did a search and couldn’t find anything on that issue. So I had done all I could, I went to the Lemon64 forum to see if I could get any feedback on the issue. Someone pointed me to Ray Carlson’s 1541II troubleshooting text file, and after reviewing it there was a reference that the issue may be the SRAM and if not that the next would possibly be the DOS Rom.
The SRAM socket was an ugly thing so I figured I would start replacing it. I pulled that cut up socket and installed a new old stock one I had around. That didn’t fix the issue though.
Here is the old “socket” (for U5) after removing the solder. The socket for the 7406 (U7) is also desoldered. That socket was not seated flush to the board and was leaning toward the U5 socket making it just a bit too tight a fit. I put it down flush to the board like it belonged.The board after removing the socket.New Old Stock socket on the left and the original “socket” on the right.Here is the new socket installed for U5 before putting the chips back. Yes it seems to be a gold plated socket.
Next I desoldered the SRAM chip from my spare 1541 board as it is the same type of chip on it. I installed the salvaged chip and the drive worked. Well it quit blinking constantly.
I then assembled the drive and connected it back to my Commodore 64. I went to check the status and it came up normally. I went to read a disk and it just error blinked. So I took the top back off of the drive, it seems the head wouldn’t move under it’s own power. I checked if it was free, and it would move with the power off, but there is some resistance. I don’t know how free it should normally be though. I then used the Alps drive test built into the Final Cartridge III+ to move he head around, it moved out but it didn’t move back the first time. The next time it did move back. I tried a few times and then I put in a disk. I was then able to read the disk normally. I read a few of the programs on it and it seemed to be working again.
I am going to get some silicone grease put on the rails to keep them freed up. I hope this drive will keep on working properly now. I am on to getting a proper power supply wrapped up for it as well.
I currently have a 1541 and a 1541ii drive. Neither (as well as the third parts drive) came with their Transit Card. I found info on the cards at Ray Carlson’s site. The cards are to protect the heads from banging around and getting damaged while being transported. They do a combination of pushing the head to the back by the head stop position and hold it there during transport to prevent damage to the drives.
So I took the images from Ray’s site into Gimp 2 and recreated the text and boxes etc. I did grab a color copy of the commodore logo from a Google search, and put on it to replace the original. It worked out great, except my printer can’t handle cardstock that is stiff enough to make the cards. I did a test print on some cardstock, but it was too lightweight. I then used that as a template to mark and cut one onto a heavier piece of stock that worked out very well. The overall dimensions minus the back tab are 5.25″ by 5.25″ with the 7/8th inch tab offset on the back. The card needs to be stiff enough that the tab on the back does not bend when inserted. If the card it too wide, of course it won’t fit into the drive. If it it too deep it will not let you latch the drive shut on it. The second card I cut from the thicker material did fit my 1541ii drive fine, but my Alps drive didn’t latch because it was hitting the front of the card just a little bit. I knew it was slightly deeper than the original I had printed, but that showed there isn’t much wiggle room in there. I trimmed that little bit of excess off of the front of the card and it fit perfectly in to the ALPS drive.
The shape of the card is based on the 251171-003 that fits the 1541, 1541ii and 1571 drives. It is a bit of a pity that I spent so much time recreating the card graphics, but I can’t print one on heavy enough stock with my printer. Overall I think it turned out well though.
Yes, I know I did not put in the proper foreign characters..
The base information for the card was from Ray Carlsen’s site:
I also have a Commodore 128 and original power supply. The supply was in working order. As console5.com had a capacitor kit for it, I figured I would take care of replacing the Capacitors in it. The main trick is that my supply’s model number doesn’t match the contents.
The model on this drive seems to indicate the internal supply should be 310416-05 but the internal is actually a Mitsumi 252449-01. I checked the supply before so I knew which kit I needed.
The supply came with 4 plugs in the screw holes in the bottom. They aren’t always the easiest to get out. One was already missing and the next two came out easily. The final one I ended up drilling a small hole in it to pull it out. I wasn’t worried about putting them back in.
The supply with the original Capacitors.The new Capacitors.
This a rather simple job. There are only two capacitors in this model of supply. The replacement ones are a good bit shorter, and have a very slightly smaller diameter. They are good quality and 105 Degree rated, as well as low ESR types for proper operation in this switching power supply.
Here you can see all of the flux still over the bottom of the board from the factory.Here is the board after I switched the Capacitors and cleaned the flux from it.
Here is the board after installing the capacitors. I also touched up a few other connections. I cleaned the old flux from the board as well, it looks much better cleaned up.
Here is the completed supply reinstalled in the case with the old capacitors beside it. I tested them and they do appear to likely be fine, but I don’t have way to test them for power leakage that happens with capacitors as they age. I trust the supply better with the new capacitors in it and expect the supply will be more reliable long term.
I ordered in a Final Cartridge III + Kit from bruktmoped on Ebay. Considering the distance coming from Norway to the US it arrived more quickly than I expected. The parts in the kit were of good quality. The board was very nice, the resistors and diodes had “real” leads like they used to 20 years ago, not the ultra thin ones that are typical of today’s cheap resistors that I get in from the east. Yes, I buy the cheap stuff for my hobby work. I don’t know if they were new old stock like some I have purchased, or if you buy them from an electronics supplier that they are still like that. Either way, I couldn’t have been more pleased with the quality of the parts.
The Final Cartridge III+ is a reproduction of the old Final Cartridge III. The chip came already programmed. You can apparently make your own up with additional programs, but mine here is just setup as bruktmoped shipped out the Eprom. I laid over the electrolytic capacitors and raised the LED off the board, as I was installing this into a 3d printed cartridge case that I again picked up from ibuy24 on Ebay. I have picked up a number of 3d printed cartridge cases from ibuy24 now.
Here is the assembled board.
The only thing that was lacking was a jumper (and instructions) on what to do with JP1 there. I didn’t know what that was for, and no instructions came with the kit. I did initially try it without the jumper at all and it did not operate at all like that I did some searches on the FCIII+ and found some pictures and a bit of info on that. That jumper seems to set the board up for the type of Eprom that is on the board. For the size of Eprom the board came with, it needs to be in the left position. I did install a jumper header though rather than soldering in a permanent jumper. To get the case to fit I had to use an extra short jump, which I did happen to have in my surplus jumper bin.
It fits great.Here is the top cover which I drilled for the Freeze and Reset buttons.Here on the front I drilled for the LED.Here on the back I hollowed out on the back side so the LED could get closer to the surface. I also had to take a little out of that support platform around the screw standoff .
So I drilled out for the Reset and Freeze buttons on the top as well as the LED with my drill press. The drill press gives more control than a hand drill, but you could do it with one. I would probably have used my Dremel instead of a hand drill though if I didn’t have the drill press. My drill press isn’t anything fancy, it is just the cheap model from Harbor Freight which I picked up for around $50 with one of their coupons. I did have to take a little out of that support area for some clearance issues for the short jumper as well. The case came with a nice brass thread for the screw as well, which I think was a nice touch. Another nice touch as you can see the case has an insert plate for the label area. I am going to make a custom label for on it before securing it permanently to the case.
Here is the cartridge installed into the Commodore 64 and powered up.
Here is a quick view of the menu system on it. You can navigate with the function keys and select the option with the Commodre “C=” Key. You can alternately navigate the menus with a Joystick, or I guess a mouse if you have a compatible one.
I really enjoyed putting this kit together. The board and components were of good quality, and it and was a lot of fun for someone like me that is. I would far rather put stuff together to use than buy it prebuilt. It isn’t like I did a lot, although the case took a bit of time to get the buttons just right and such. While the bare board looks very nice, I am happier with a cartridge in a case. The case makes inserting the cartridge so much easier because it aligns it to the slot, and aids removal by providing a good grip as well as protecting the circuitry from static shock and such. The case has a good solid feel to it as well.
I worked up a little label for it. It looks a bit better with it.
Muldrf's Hobbytronic 